Core oils and process for producing same



35 4 of binder collects closely around the point of Patented Sept. 8, 1931 UNITED; STATES PATENT OFFICE EDWARD IE. MOARDLE, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO KLIPST'EIN AND COMPANY, OF N YORK, N. Y., A CORPORATION OF NEW JERSEY OILS AND PROCESS FOR PRODUCING SAME No Drawing.

. be used in the molding and baking of foundry cores, an oil or a pitchy substance is employed as the principal binder. Oils are preferred for castings of grey or malleable iron, brass, bronze, aluminum, and non-ferrous metals and alloys generally. Oils have recently found increased favor in competition with the less costly pitches in preparing cores for steel and semi-steel castings.

An efficient core oil should possess four distinct properties.

First. It should form a film closely adherent to the sand grains. Oil and sand are manually or mechanically mixed at room temperature and hence for even distribution of film the oil viscosity must be maintained at a fairly low point. Thus only a limited quantity of non-volatile solid constituent, such as rosin, can be incorporated in core oil without the addition of excessive amounts of volatile solvent which after baking becomes valueless.

Second. The oil film during baking should contract markedly. Contraction may be due to the decrease in bulk through solvent evaporation.- It is also due to the preponderance of film self-cohesion over adhesion of film to the sand surface. In other words, the portion of film'adjacent to the actual point of contact of two sand grains is drawn toward this point of contact. Thus a sizable globule contact, where it is needed, while the film away from this point, and hence non-essential to this binding, has been considerably thinned. In this way the volume of voids in a given core is increased resulting in a more porous and better ventilated mass.

' Third. The core film should possess therinal stability after baking. At and approaching temperature of pouring molten metal, the film should undergo very little decomposition or cracking. Such decomposition is always accompanied by the voluminous production of gas "whose pressure tends to distort or map the core. During pour- Application filed March 14, 1930. Serial No. 435,959.

ing the temperature rise is so sudden that the kindling temperature of the film material is quickly reached. Hence, if durin this short interval the film is not cracke it will quickly burn away Without the development of excessive internal pressure on the core as a whole.

Fourth. The oil film should possess a bi h degree of imperviousness to moisture. T e entrance of water weakens the film so that the baked core is liable not only to easier breakage but also to deformation from its own weight during storage.

Foundry experience has to date shown that the above listed properties are possessed in the greatest degree by drying oils, or mixed with rosin and solvent. Semi-drying oils' that is, those with iodine numbers less than 140have been found less satisfactory. It is at present generally accepted that the best material for core oil is linseed oil, either raw or boiled. Hence the best core oils at present contain linseed oil, usually mixed with rosin and a naphtha thinner. The strength of the core baked with such oils is in almost direct proportion to the linseed oil content of the core oil. Hence, a given quantity of sand may be bound with less of a high linseed core oil than with one containing a low percentage of linseed. Thus the cost of a high grade core oil has been vitally dependent upon the market value of linseed oil or other drying oils with high iodine numbers such as perilla, China wood, and menhaden. Inasmuch as perilla, China wood, and menhaden oils may replace linseed oil in many aint and Varnish formula, the market price of these oils fluctuates in sympathy with that of linseed oil.

This invention makes possible the use of the less costly, lower iodine number oilseither alone those of the semi-drying class, such as soyai the oil employed. Thus if equal weights of power of the core oil films now the glyceryl ester of rosin be heated separately with equal weights of perilla, linseed. soya-bean, or corn oils, the binding powers of the resultant core oil are equal within the limit of experimental error in testing core strengths. Similar results occur if for the rosin glyceryl ester there be substituted other rosin esters or esters of other natural resins such as the glyceryl ester of Pontianac gum.

The thermally effected chemical combination of the essentially neutral resin with the drying or semi-drying oil produces a base which, on dilution with a solvent to produce a core oil, possesses the four previously mentioned desirable properties to the highest degree. It has the additional pro erty of being extremely heat-resistant. ore baking conditions which would destroy the binding used have a much less detrimental efi'ect upon the product here described. Imperviousness to moisture is extreme, comparable to that of a spar varnish. Sand wetting power, contraction on baking, and core-porosity are extremely high, while tendency toward thermal decomposition and gasification are extremely low. All these effects are the result of the close chemical combination made possible in the heat treatment of an essentially neutral resin with a fixed oil having an iodine number over one hundred. The baked film is tougher, more elastic. and less brittle than that of a core oil made by mixing a highly acidic resin with such a xed oil.

My invention may be illustrated by the following examples:

E'mample 1.-Heat together three pounds of crude corn oil and two pounds of ester gum to 560-580 F. during one half hour. Hold at this temperature for ten minutes, and add one and three quarters pounds of cold low viscosity parafiin oil. Allow to cool and addthree quarters of a pound of mineral spirits. The product is one gallon of core oil. Example 2.Heat together two pounds of soya-bean oil and three pounds of the glyceryl ester of natural Pontianac gum to 50 0520 F. during one hali' hour. and hold at this temperature for one half hour. At this temperature add one pound of cold low viscosity paraffin oil and allow to cool. When cold add one and one half pounds of mineral spirits. The product is one gallon of core oil.

In the above examples the desired chemical combination between the fixed oil and the resin of low acidity will take place between 500 F. and 580 F., that is, at varnish-making temperatures, depending upon the period of heating.

The core oils hereinbefore described and coming within the scope of my invention are of great commercial value and utility in that they can be produced from the cheap semidrying oils yet 'ving a product that will have all of the a vantageous properties possessed by a core oil made largely from the more expensive linseed oil.

The examples above given are not to be considered as limitative of my invention. Nor is m invention limited to the drying oils specifica ly mentioned in said examples, as the use of all oils having an iodine number over one hundred comes within the scope of my invention;

What I claim is 1. The process for the production of core oils which consists in reacting at temperatures between 500 and 580 F. on a fixed oil of any iodine number over one hundred with the glyceryl ester of rosin.

2. The process for the production of core oils which consists in reacting at temperatures between 500 and 580 F. on a fixed oil of any iodine number over one hundred with the glyceryl ester of rosin, and subsequently diluting the resulting product to the proper viscosity.

3. The process for the production of core oils which consists in reacting at temperatures between 500 and 580 F. on a fixed oil of any iodine number over one hundred with the glyceryl ester of any naturally occurring acidic resin, and subsequently diluting the resulting product to the proper viscosity.

4. The process for the production of core oils which consists in reacting at temperatures between 500 and 580 F. on a fixed oil of any iodine'number over one hundred with an ester of rosin made from a trihydric alcohol, and subsequently diluting the resulting product to the proper viscosity.

5. An oil for use in making foundry cores comprising a fixed oil having an iodine number over one hundred and the glyceryl ester of rosin, and a solvent to give the desired vlscosity.

6. An oil for use in making foundry cores comprising a fixed oil having an iodine number over one hundred and the glyceryl ester of a naturally occurring acidic resin and a solvent to give the desired viscosity.

7. An oil for use in making foundry cores comprising a fixed oil havingan iodine number over one hundred and rosin whose acidity the required viscosity by a solvent.

' 9. An oil for use in making foundry cores which comprises the reaction product between a heated fixed oil of any iodine number over one hundred and a heated. glyceryl ester of rosin, the resulting product being diluted in a solvent to the desired viscosity.

' 10. An oil for use in making foundry cores which comprises the reaction product between a heated fixed oil having an iodine number over one hundred and a resin of lower acid value than rosin, the resulting product being diluted in a solvent to the proper viscosity. 10 11 An oil for use in making foundry cores which comprises the reaction product, be-

tween heated soya-bean oil and the heated Eiycetyl ester of rosin, the resulting product mg diluted in a solvent to the desired vis- 15 cosity.

p This specification signed this 12th day of March, 1930.

-- EDWARD H., MGARDLE. 

